Rotary washover shoe



1951 M. L. CLAYTON ROTARY WASHOVER H0E Filed Sept. 25, 1949 lnverfl'or Max L. Clmfion u his Aikorneg Patented Dec. 4, 1 951 ROTARY WASHOVER SHOE Max 1.. Clayton, Iberia, La., assignor to Shell Development Company, San Francisco, Calif., a

corporation of Delaware Application September 23, 1949, Serial No. 117,436

'1 Claim. (01. 255- 61') This invention relates to the art of well drilling and pertains more particularly to a'rotary cutting tool which may be lowered on the end of a string of tubing for cutting sand and formation debris from around another Well tool which is.

lodged in a well borehole.

In drilling an oilwell, it occasionally happens that a well drilling tool, or a portion of the drill string,,becomes disconnected from the drill string suspended from the well derrick and is lost in the well. Before an overshot or fishing tool can be lowered into the wellborehole, the lost drilling tool or fish may become covered with cavings vof sand, formation debris or rock fragments.

v the lower end of a tubing string. Alternatively,

the washover shoe may be fixedly attached to the lower end of a fishing tool which is in turn carried at the lower end of a tubing string. A rotary washover shoe comprises a tubular cutting head or tool having a plurality of teeth directed downwardly when the tool is attached to a tubin string. As the rotary shoe cuts the debris from around the fish, the shoe is lowered so that the fish rises within the shoe. The main disadvantages with the washover shoes no'w usedin well drilling are, first that the shoes have a tendency to cut into the walls of a borehole as the shoe is lowered and, second, that cuttings often become trapped between the fish and the surrounding shoe thereby wedging the fish and shoe, and thus immobilizing the shoe until sufiicient torque has been applied to the tubing string to free the shoe, which may sometimes cause a failure by twist-off.

It is, therefore, an object of the present invention to provide a rotary washover shoe adapted to cut material from around a fish in a well borehole without permitting cuttings to become wedged between the shoe and the fish.

Another object of this invention is to provide 1 an improved washover shoe whose teeth do not Figure 1 is a perspective view, partly in cross .section, of one embodiment of the present rotary washover shoe.

Figure 2 is a top view of the embodiment of Figure 1.

Figure 3 is a cross-sectional view taken along the line 3--3 of Figure 2.

Figure 4 is a diagrammatic view of a. well borehole having positioned therein a tubing string with the present washover shoe afiixed to the lower end thereof.

Referring to Figure 1, the present rotary wash:- over shoe comprises a tubular body member II equipped with suitable connecting means at, one end, such as internal threads I2, for attaching said body member II to a drill or tubing string I3, as shown in Figure 4. The other end of tubular body member II carries, a plurality of teeth I4 or rock cutting means which may be afiixed to said body I I in any suitable manner, or formed integrally with,'or cut longitudinally therein, as illustrated in Figure 1.

The size and number of teeth may vary, as desired, depending upon the size of the body member II and the formation in which it is to be used.

If desired, a plurality of auxiliary reaming teeth I5 may be aflixed in any suitable manner, as by welding, on the outside of said body member II. While satisfactory reaming action may be obtained with the reaming teeth I5 affixed at any point on the outer surface of the body member II, said teeth I5 are preferably welded to said body member II at a point adjacent the cutting teeth I4 to reinforce the cutting faces I6 of said teeth I4 and to form a unitary tooth of substantially greater thickness than that of the body member II. The body member II and. the teeth I4 and I5 are made of a wear-resistant steel suitable for well drilling operations. Preferably, the teeth I4 and I5 may be made of, or faced with, a wear-resistant alloy, for example, boron or tungsten carbide.

It has now been found that a number of advantages to drilling operations may be realized if the annular segments forming one of the faces of the teeth I4 and I5 are beveled, slanted or chamfered, preferably, the entire thickness of both teeth I4 and I5, as shown at I! in Figures 1 and 3. That is, with the head II positioned as shown in Figure 1, the annular faces of the teeth I4 and I5 are slanted or beveled downwards from the inner to the outer cylindrical surfaces of the head II, or from point Ila downwards to point I'll), whereas in conventional rotary shoes, now

' biting into the W311 of the well.

in universal usage, said segmented annular teeth are beveled or slanted in the opposite direction, that is, from the outer cylindrical surface of the head H downwards to the inner cylindrical surface thereof wherebythe high side of the teeth are on the outside circumference. The teeth may be beveled at any desired angle, preferably at an angle of about 45. For. purposes of definition in the present specification and claims; teethhaving annular faces beveled or slanted in the manner described hereinabove will be termed teeth with outwardly beveled annular faces.

Many advantages are realized by using rotary washover shoes having the outer edges' of the V teeth beveled in the above=described man ner;' one of the most important advantages being that of increased life to the bit. H V V Likewise, greater efficiency is realized when using a rotary washover shoe of the present 'design since the tendency of the shoe to dig into 'the walhof the borehole 'when washingover a "fish is eliminated :by' bevel-ingstheouter edge :of

the rotary shoe, and thus preventing it from Additionally, the beveled outer edge of the shoe tends topush 7 broken "bit teeth, :orother debris, in an outward direction, and thus prevent themirombecoming trapped-between ther-otary shoeand th'eAm-ain I fishpwhereas this difiiculty is --often encountered With conventionally beveled bits.

In a comparison test of the present rotary shoes with conventional rotary'sh'oes, three conventionalshoes were :in:-a=-we1l-at a depth of -about 5200 -ft.andused to' ream:-said wellever ed-istanees of 35 ft., 12 ft. and l l ft,respectively,

two rotaryshoes-of the presentdesign were employed. "The firstone pushed aside the'eu tters lei-t in thehole by the previous hi't and then -drilled 244-it. The second one reame'd153-ft. before the threads (Fig 1) failed, butthe cutting teethwere stillinusable condition,

Table of comparison test In fishing operations, the washover shoe II is coupled to the lower end of a wash pipe I3 (Fig. 4) or to the lower end of an overshot carried by said wash pipe. The wash pipe I3 is in turn 5 suspended in a well borehole 19 from a well derrick 26. Means (not shown) for rotating the pipe 13 and for pumping a liquid therethrough arealsc provided. The-comb'ined -actions of outti ng by the rotating shoe:- -il-'-arid thefiowing of the liquid pumped through said pipe l3 removes the sand or formation debris 2| from about the fish 22. -T-his operation is continued until the shoe and overshot l8 are lowered over the fish -22 which rises within the shoe, overshot and -W'ashpipe; A fter sufficient material 21 has been washed"away,*an upward pull on the wash pipe -13 afir-mlyanchorsthe overshot about the fish 22 which may be'then pulled out of the well borehole.

I claim as my invention:

7 A: rotary washover shoeeomprising-a tubular -body' rnembernopensat -both ends, meansecarried 1on one said of said bodymem' ber for attaching to a string. of pipe,-"a!plurality of cutting teeth 25 termed at the othe'r endi of said body 1 member and projecting longitudinally therefrom, and 1a plurality-or aiX-i liary reaming -teethiaffixed in spaced ine'lationsh-ip in a singlei ow to the outer of said body :rnember adjac'ent the cutl 'ig f-aoes of said cutting teeth, 1 the spaces 1 between said anai-nary teeth f-orniinglongitudinal water: courses through which drillingfluid 'may 1 ate each of said cuttingcand reaming teeth hay g outwai dly beveled an'nular faee's fiush 'wi th eachother in wsingle lane.

hCLAY IQN.

-REFERENGES- CITED 40 Thefollowing references are ofreoord in' -the file= of this patent:

UNITEDSTATES PATENTS Number 

